An imaging spectrometer is a device that takes images that include information about the different wavelengths of light. When this device is combined with specialized types of input light, such as fluorescence or Raman inputs, it can be used to differentiate between different materials that are indistinguishable to the naked eye in a nondestructive manner. An imaging spectrometer takes many spectral data points from an image at the same time, also making it easier to align to a target.
Many small spectrometers contain imaging sensors but are not imaging spectrometers. Most of these small spectrometers contain dispersive elements or conduct line-based Fourier transforms so they measure the spectra of a single pixel or a limited number of pixel much smaller than the number of points on the imaging sensor. They can only take an image if raster scanned. Dispersive methods do not take advantage of spectral multiplexing and cannot take advantage of the irregular sampling techniques outlined in this work. There are also miniature Fourier transform spectrometers that are single-point spectrometers, which do not perform direct imaging.